An am signal is represented in time domain as s(t) = 4cos(1800t) + 10cos(2000t) + 4cos(2200t). Sketch the spectrum and determine bandwidth (b), total power (pt), and modulation efficiency ().
Answers
Answer:
I don't know what you think about it out on
Concept:
The AM signal is conveyed by varying its amplitude, and we may answer this question by applying its notions.
Given:
AM signal s(t) = 4cos(1800t) + 10cos(2000t) + 4cos(2200t)
Find:
Sketch the Spectrum
Determine bandwidth
Determine Total Power
Determine efficiency
Solution:
Spectrum is given in the attachment
From the signal equation we can easily know that Wc is 2000
As, Wc - Wm is given as 1800 in the signal equation
Wc - Wm = 1800
We have given Wc as 2000
2000 - Wm = 1800
Wm = 2000 - 1800
Wm = 200
We know that the bandwidth is twice of Wm so,
Bandwidth = 2 × Wm
Bandwidth = 2 × 200
Bandwidth = 400 Hz
Total power is the summation of Power of signal and Power of side bands
Total Power = Power Side Bands + Power of Signal
Total Power = (Ac M / 2)² + Ac² / 2
From signal wave equation (Ac M / 2) is 4 and Ac is 10.
Total Power = 4² + 10² / 2
Total Power = 16 + 50
Total Power = 66 Watt
Efficiency = Power of Side Bands / Total power
Efficiency = (Ac M / 2)² / 66
Efficiency = 16 / 66
Efficiency = 0.24242
So the Bandwidth of the AM signal wave is 400 Hz, Total Power is 66 Watt, and Efficiency is 0.24242.
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